In some cases the threats had the desired effect, as newspapers decided to drop their coverage of sensitive issues, according to a study carried out by Mid Sweden University in Sundsvall.
The report details a number of specific incidents, including that of a journalist whose post box was blown to pieces. In another case, an editor was threatened in his office by an unwanted visitor bearing a pair of scissors.
Calle Mathisson from regional newspaper Blekinge Läns Tidning is one of very few editors willing to comment on the phenomenon.
"Last year we had somewhere between five and seven threats. The number of politically motivated threats has increased during this decade, but we have it under control.
"Generally those issuing the threats are people who are angry about something that has been written," he told the authors of the report.
Over the last few years, studies have shown that local politicians are exposed to more threats than ever before. According to the report, politicians and journalists often find themselves used as pawns in the same game.
Last week Blekinge Läns Tidning received a package containing a cartridge that was intended for a politically active group.
"In my experience it can often begin as a threat to politicians before spreading to journalists. The end result is a threat to democracy and a more closed society as people become more careful and more afraid.
"Society needs to be on its guard and do something about these threats," said Calle Mathisson.